The invention relates to a novel detection pixel micro-structure allowing the simultaneous and continuous detection of several discrete optical frequencies, wherein a plurality of such pixels can be combined to form a focal plane array for a multi-spectral digital camera.
As camera technology continues to advance, there is a growing demand for multi-spectral detectors for advanced camera systems featuring better intelligence functions such as target discrimination and identification, while retaining the maturity and low-cost structure of very large scale integration (VLSI) processing. A multiplicity of defense and commercial programs require the utilization of infrared focal plane arrays for the acquisition of a broad range of spectral, temporal and spatial data, with a demand on small device size, low power consumption, low premium and utilization costs, compatibility to 30 Hz video frame rate and with at least a 1024×1024 pixel resolution.
So far, multiple spectral band measurements have been achieved using separate focal plane arrays with fixed filters, a mechanical filter wheel, or a dithering system with a striped filter, or an interleaved array of single-spectral pixels having different spectral responses, or a quantum well optoelectronic structure (e.g. QWIP devices). These approaches are expensive, and require cumbersome spatial alignment and temporal registration, or require complex lithographic fabrication processes. Thus, a single focal plane array with multi-spectral capabilities that circumvent these problems is very desirable because it can significantly simplify the design, and reduce the size, cost, weight and power consumption of the camera system.